Imaging Apparatus and Method for Manufacturing Microlens Array

ABSTRACT

An imaging device ( 3 ) including a plurality of pixels ( 3   a ) having a photoelectric conversion function, and a microlens array ( 1 ) including a plurality of microlenses ( 1   a ) that form subject images on these plurality of pixels ( 3   a ) and are arranged in a matrix are disposed so as to face each other. The microlens array ( 1 ) includes grooves ( 20 ) in a lattice form between the microlenses ( 1   a ) that are adjacent to each other. The depth of the grooves ( 20 ) is larger than a half of the thickness of the microlens array ( 1 ). Accordingly, it is possible to achieve an imaging apparatus that is easy to manufacture, has a simplified configuration and can capture a clear image and in which an influence of stray light and cross talk are reduced sufficiently.

TECHNICAL FIELD

The present invention relates to an imaging apparatus. In particular,the present invention relates to an imaging apparatus in which amicrolens array including a plurality of microlenses is arranged on asubject side of an imaging device having a large number of pixels.Further, the present invention relates to a method for manufacturingthis microlens array.

BACKGROUND ART

In a digital still camera market that has been expanding in recentyears, there is a growing need for a small and thin camera havinggreater portability. Circuit components such as LSIs for performing asignal processing have been miniaturized with a high functionality byachieving finer wiring patterns. Also, small recording media with alarge capacity have become available at low cost. However, an imagingsystem constituted by a lens and a solid-state imaging device such as aCCD or a CMOS has not been miniaturized sufficiently, and it is desiredthat a small imaging system be developed also for realizing a camerawith greater portability.

As a configuration for achieving the miniaturization of the imagingsystem, a configuration using a lens array optical system in which aplurality of microlenses are arranged on a plane has been known. The useof the lens array optical system makes it possible to reduce thethickness of the imaging system in an optical axis direction, and tokeep an aberration to be relatively small because individual microlenseshave a small diameter.

JP 59(1984)-50042 B discloses an imaging system using such a lens array.This imaging system includes a microlens array having a plurality ofmicrolenses arranged in a plane, a pinhole mask having a plurality ofpinholes formed in a plane so as to be in a one-to-one correspondencewith the microlenses and an image plane in which light that has passedthrough each of the pinholes forms an image, in this order from asubject side. Each of the microlenses forms a reduced image of thesubject on the pinhole mask, and the individual pinholes allow lightcorresponding to different portions of this reduced image to passthrough (i.e., they sample the light). As a result, a subject image isformed on the image plane.

However, in the above-described imaging system disclosed by JP59(1984)-50042 B, since the resolution of the subject image formed onthe image plane depends on the number and density of the microlenses(namely, the pinholes), it has been difficult to improve an imagequality. In other words, because the arrangement of units eachconstituted by a pair of the microlens and the pinhole determines thearrangement of sampling spots of the image to be obtained, in order toachieve a higher image quality, it is necessary both to increase thenumber of the above-mentioned units and thus the number of samplingspots and to reduce the size of the individual microlenses and thus anarrangement pitch of the above-mentioned units. However, there is alimit on the miniaturization of the microlenses, so that it has beendifficult to achieve a higher resolution. Further, since a light fluxreaching the image plane is restricted by the pinholes, there is asignificant loss of the light amount, leading to a problem insensitivity.

JP 2001-61109 A discloses an imaging system using another lens arraythat solves the problem described above. As shown in FIG. 12, thisimaging apparatus includes a microlens array 111 having a plurality ofmicrolenses 111 a arranged in the same plane, a partition layer 112formed of a lattice-shaped partition 112 a for separating opticalsignals from the individual microlenses 111 a so as not to interferewith each other and a light-receiving element array 113 having a largenumber of photoelectric conversion elements 113 a arranged in the sameplane, in this order from a subject side. One microlens 111 a, onecorresponding space isolated by the partition 112 a and a plurality ofthe photoelectric conversion elements 113 a form one image forming unit115. In each image forming unit 115, the microlens 111 a forms a subjectimage on the plurality of the photoelectric conversion elements 113 acorresponding to this microlens 111 a. In this manner, a captured imageis obtained for each image forming unit 115. The resolution of thiscaptured image depends on the number of the photoelectric conversionelements 113 a (the number of pixels) forming one image forming unit115. Since positions of the individual microlenses 111 a relative to thesubject are different, the position at which the subject image is formedon the plurality of the photoelectric conversion elements 113 a differsfrom one image forming unit 115 to another. Consequently, the obtainedcaptured image differs from one image forming unit 115 to another. Theseplural captured images that are different from each other are subjectedto signal processing, thereby achieving a single image.

In this imaging apparatus, since the number of pixels forming each imageforming unit 115 is small, the captured image obtained by each imageforming unit 115 has a low quality. However, by carrying out the signalprocessing using the captured images that are obtained respectively bythe plural image forming units 115 and shifted slightly from each otherand re-forming an image, it is possible to achieve a picture whose imagequality is as high as an image captured using a large number ofphotoelectric conversion elements.

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

In the imaging apparatus shown in FIG. 12, when light from the microlens111 a enters the photoelectric conversion element 113 a of an adjacentimage forming unit 115, which does not correspond to this microlens 111a (this phenomenon is called “cross talk”), stray light is generated, sothat a high quality image cannot be re-formed or light loss occurs. Thepartition layer 112 is provided for preventing this cross talk.

If the partition 112 a becomes thicker (in a direction parallel with theplane in which the photoelectric conversion elements 113 a arearranged), the number of the photoelectric conversion elements 113 aincluded in one image forming unit 115 decreases, thus lowering theimage quality. Therefore, it is preferable that the partition 112 a isthin.

However, a thinner partition 112 a makes it difficult to manufacture thepartition layer 112 and assemble the imaging apparatus.

It is an object of the present invention to solve the conventionalproblem described above and to provide an imaging apparatus that is easyto manufacture.

Means for Solving Problem

An imaging apparatus according to the present invention includes animaging device including a plurality of pixels having a photoelectricconversion function, and a microlens array including a plurality ofmicrolenses that form subject images on the plurality of pixels in theimaging device and are arranged in a matrix. Also, the microlens arrayincludes grooves in a lattice form between the microlenses that areadjacent to each other, and a depth of the grooves is larger than a halfof a thickness of the microlens array.

A first method for manufacturing a microlens array according to thepresent invention includes obtaining by resin molding a microlens arraywhose one surface is provided with a plurality of spherical oraspherical microlenses and whose other surface is flat, and forminggrooves in a lattice form on the other surface of the microlens array bya light irradiation from the other surface.

A second method for manufacturing a microlens array according to thepresent invention includes obtaining a microlens array whose one surfaceis provided with a plurality of spherical or aspherical microlenses andwhose other surface is provided with grooves in a lattice form and isflat except for the grooves, and processing lateral surfaces of thegrooves to be black by injecting a solution prepared by dissolving ablack coating material in a solvent into the grooves.

Effects of the Invention

In accordance with the present invention, since a portion having afunction similar to the conventional partition is provided in themicrolens array, it is possible to achieve an imaging apparatus that iseasy to manufacture, has a simplified configuration and can capture aclear image and in which an influence of stray light and cross talk arereduced sufficiently.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a partially broken perspective view showing animaging apparatus according to Embodiment 1 of the present invention.

[FIG. 2] FIG. 2 is a perspective view, seen from a surface on asolid-state imaging device side, showing a microlens array used in theimaging apparatus according to Embodiment 1 of the present invention.

[FIG. 3] FIG. 3 is a sectional view showing the microlens array seen ina direction indicated by arrows taken along a line III-III in FIG. 2 inEmbodiment 1 of the present invention.

[FIG. 4] FIG. 4 is a sectional view showing how stray light is generatedin the case where the depth of grooves of the microlens array is a halfof the thickness of the microlens array.

[FIG. 5] FIG. 5 is a sectional view showing how stray light issuppressed in the case where the depth of the grooves of the microlensarray is 70% of the thickness of the microlens array.

[FIG. 6] FIG. 6 is a sectional view showing another microlens array usedin the imaging apparatus according to Embodiment 1 of the presentinvention.

[FIG. 7] FIG. 7 is a sectional view showing a microlens array used in animaging apparatus according to Embodiment 2 of the present invention.

[FIG. 8] FIG. 8 is a sectional view showing another microlens array usedin the imaging apparatus according to Embodiment 2 of the presentinvention.

[FIG. 9] FIG. 9 is a partially broken perspective view showing animaging apparatus according to Embodiment 3 of the present invention.

[FIG. 10] FIG. 10 is a sectional view showing a microlens array used inan imaging apparatus according to Embodiment 3 of the present invention.

[FIG. 11A] FIG. 11A is a sectional view showing a process of an exampleof a method for manufacturing a microlens array according to the presentinvention.

[FIG. 11B] FIG. 11B is a sectional view showing a process of an exampleof the method for manufacturing a microlens array according to thepresent invention.

[FIG. 11C] FIG. 11C is a sectional view showing a process of an exampleof the method for manufacturing a microlens array according to thepresent invention.

[FIG. 11D] FIG. 11D is a sectional view showing a process of an exampleof the method for manufacturing a microlens array according to thepresent invention.

[FIG. 12] FIG. 12 is an exploded perspective view showing a schematicconfiguration of a conventional imaging apparatus.

DESCRIPTION OF THE INVENTION

In the above-described imaging apparatus according to the presentinvention, it is preferable that a material of the microlens array isformed of a light-transmitting resin. This reduces the light loss andmakes it possible to capture a clear image. Further, the use of theresin material allows easy manufacturing.

Also, in the above-described imaging apparatus according to the presentinvention, it is preferable that the microlens array is a plano-convexlens array whose one surface is provided with the microlenses and whoseother surface is provided with the grooves and faces the imaging device.This makes it possible to reduce the influence of stray light and crosstalk sufficiently within the limited range of the thickness.

Further, in the above-described imaging apparatus according to thepresent invention, it is preferable that a light-absorbing material isapplied to lateral surfaces of the grooves. This makes it possible toreduce stray light and cross talk further.

In this case, it is preferable that the light-absorbing material isblack. This makes it possible to reduce stray light and cross talkfurther.

Moreover, in the above-described imaging apparatus according to thepresent invention, it is preferable that a width of the groovesincreases toward the imaging device. In this way, when the microlensarray is formed with a mold, it is released from the mold more easily,thus improving the productivity.

Additionally, in the above-described imaging apparatus according to thepresent invention, it is preferable that a second material having asmaller light transmittance than a first material forming the microlensarray is filled in the grooves. This makes it possible to reduce straylight and cross talk further. Moreover, the second material is filled inthe grooves, whereby the strength of the microlens array improves.

In this case, it is preferable that the second material contains amaterial having a light-absorption function. This prevents lightentering the second material from leaving this second material, and thusit is possible to reduce stray light and cross talk further.

It also is preferable that the second material has a larger refractiveindex than the first material. In this way, the total-reflection doesnot occur easily at an interface between the first material and thesecond material, so that light entering this interface from the firstmaterial enters the second material more easily. As a result, it ispossible to prevent stray light, which is generated by the reflection ofthe light at the interface.

Furthermore, in the above-described imaging apparatus according to thepresent invention, it is preferable that the microlens array ismanufactured by resin molding. This makes it possible to manufacture themicrolens array efficiently.

Moreover, in the above-described first method for manufacturing amicrolens array according to the present invention, it is preferablefurther to include processing lateral surfaces of the grooves to beblack by injecting a solution prepared by dissolving a black coatingmaterial in a solvent into the grooves. This makes it possible to coatthe lateral surfaces of the grooves with the black coating simply andefficiently.

The following is a description of embodiments of the present invention,with reference to the accompanying drawings.

EMBODIMENT 1

FIG. 1 is a partially broken perspective view showing an imagingapparatus according to Embodiment 1 of the present invention. Numeral 1denotes a microlens array having a plurality of spherical or asphericalmicrolenses 1 a arranged in a matrix in the same plane, and numeral 3denotes a solid-state imaging device (for example, a CCD) having a largenumber of pixels 3 a with a photoelectric conversion function arrangedin a matrix in the same plane. One microlens 1 a corresponds to aplurality of the pixels 3 a, and they form one image forming unit 5. Ineach image forming unit 5, the microlens 1 a forms a subject image onthe plurality of the pixels 3 a corresponding to this microlens 1 a. Themicrolenses 1 a are formed on the surface of the microlens array 1opposite to the solid-state imaging device 3 (the surface on the subjectside).

FIG. 2 is a perspective view showing the microlens array 1 seen from thesurface on the solid-state imaging device side. FIG. 3 is a sectionalview showing the microlens array 1 seen in a direction indicated byarrows taken along a line III-III in FIG. 2. The microlens array 1 isformed of a light-transmitting resin and is a plano-convex lens arraywhose one surface (the surface on the subject side) is provided with theplurality of microlenses 1 a and whose other surface (the surface on theside of the solid-state imaging device 3) is substantially flat. Thisother surface is provided with slit grooves 20 in a lattice form along aborder between adjacent image forming units 5. The grooves 20 in thelattice form form quadratic prism portions 22. The microlenses 1 a andthe quadratic prism portions 22 are in one-to-one correspondence. Lightfrom the subject is focused by the microlens 1 a, transmitted inside thequadratic prism portion 22, emitted from an emission portion 23 opposedto the microlens 1 a and enters the solid-state imaging device 3 facingthe emission portion 23.

Lateral surfaces of the quadratic prism portions 22 (in other words,lateral surfaces of the grooves 20, which are perpendicular to theabove-noted other surface of the microlens array 1) are coated with alight-absorbing black coating 25. Since stray light entering thislateral surface is absorbed by the black coating 25, it does not passthrough the lateral surface and does not enter the adjacent quadraticprism portion 22.

The depth of the grooves 20 (the height of the quadratic prism portion22) is larger than a half of the thickness of the microlens array 1.This makes it possible to prevent the phenomenon in which light that haspassed through the microlens 1 a is emitted from the emission portion 23of the quadratic prism portion 22 that does not correspond to thismicrolens 1 a, namely, cross talk.

This will be described in detail below.

FIG. 4 is a sectional view showing how the stray light is generated inthe case where the depth D of the grooves 20 of the microlens array 1 isa half of the thickness H of the microlens array 1.

In FIG. 4, a light flux L1 entering the microlens 1 a obliquely ishardly eclipsed by the groove 20 and reaches the emission portion 23 ofthe quadratic prism portion 22 that does not correspond to the microlens1 a that the light flux L1 has entered. Thus, in the case where a verybright object is present in an incident angle direction of the lightflux L1, the generation of stray light may cause a problem.

In the case where a light flux L2 having a smaller incident angle thanthe light flux L1 enters the microlens 1 a obliquely, a part of thelight flux L2 is eclipsed by the groove 20 and the remainder reaches theemission portion 23 of the quadratic prism portion 22 that does notcorrespond to the microlens 1 a that the light flux L2 has entered.Thus, in this case, the intensity of light entering the pixels that donot correspond to the microlens 1 a that the light flux has entered islower than that in the case where the light flux L1 enters as describedabove. Consequently, less stray light is generated.

In the case where a light flux (not shown) having a larger incidentangle than the light flux L1 enters the microlens 1 a obliquely, all ofthis light flux is eclipsed by the groove 20 and does not enter directlythe pixels that do not correspond to the microlens 1 a that the lightflux has entered. Consequently, the generation of stray light can besuppressed substantially.

FIG. 5 is a sectional view showing how the stray light is suppressed inthe case where the depth D of the grooves 20 of the microlens array 1 is70% of the thickness H of the microlens array 1.

In FIG. 5, in the case where a light flux L3 having the same incidentangle as the light flux L1 shown in FIG. 4 enters, about half of thelight flux L3 is eclipsed by the groove 20. Thus, in this case, theintensity of light entering the pixels that do not correspond to themicrolens 1 a that the light flux has entered is lower than that in thecase where the light flux L1 enters in FIG. 4. Consequently, less straylight is generated.

In the case where a light flux L4 having a smaller incident angle thanthe light flux L3 enters the microlens 1 a obliquely, at least a half ofthe light flux L4 is eclipsed by the groove 20 and the slight remainderreaches the emission portion 23 of the quadratic prism portion 22 thatdoes not correspond to the microlens 1 a that the light flux L4 hasentered. Thus, in this case, the intensity of light entering the pixelsthat do not correspond to the microlens 1 a that the light flux hasentered is lowered considerably. Consequently, even less stray light isgenerated.

In the case where a light flux (not shown) having a larger incidentangle than the light flux L3 enters the microlens 1 a obliquely, all ofthis light flux is eclipsed by the groove 20 and does not enter directlythe pixels that do not correspond to the microlens 1 a that the lightflux has entered. Consequently, the generation of stray light can besuppressed substantially.

In FIG. 5, the stray light is most likely to be generated in the casewhere the light flux L3 enters. The stray light generated in this caseis much less than that in the case where the light flux L1 enters inFIG. 4.

As described above, when the depth D of the grooves 20 is set to belarger than a half of the thickness H of the microlens array 1(D>0.5×H), it is possible to achieve a substantially sufficientlight-shielding effect. Incidentally, in the present invention, thethickness H of the microlens array 1 is defined as the thickness of themicrolens array 1 except for protruding portions of the microlenses 1 aas shown in FIGS. 4 and 5.

In the imaging apparatus of the present embodiment, since the grooves 20function as the partition 112 a in the conventional imaging apparatusshown in FIG. 12, the conventional partition layer 112 is not needed.Thus, the manufacture is easy, and the configuration can be simplified.

Although the present embodiment has described the example in which thelateral surfaces of the grooves 20 are coated with the black coating 25,they also may be processed to have a light-absorption function or afunction of attenuating light instead of the black coating 25. In thatcase, it also is possible to achieve a sufficient light-shieldingeffect. Further, even if the lateral surfaces of the grooves 20 are notsubjected to any special processing as described above, simply providingthe grooves 20 as shown in FIG. 6 can reduce the influence of straylight as long as lateral surfaces 24 of the grooves 20 have a necessaryand sufficient roughness.

In each image forming unit 5, the microlens 1 a forms the subject imageon the solid-state imaging device 3. Each of the pixels 3 a of thesolid-state imaging device 3 converts the incident light into anelectrical charge. The images obtained by the individual image formingunits 5 are slightly different because the positions of the microlens 1a and the pixels 3 a relative to the subject differ from one imageforming unit 5 to another. By synthesizing these plural images obtainedby the individual image forming units 5 by, for example, theabove-described method of JP 2001-61109 A, it is possible to obtain animage with a far higher resolution than the number of pixels 3 aincluded in one image forming unit 5.

EMBODIMENT 2

FIG. 7 is a sectional view showing a microlens array 1 used in animaging apparatus according to Embodiment 2. The elements that are thesame as those in Embodiment 1 are assigned the same reference numerals,and the description thereof will be omitted.

In Embodiment 2, the width (the dimension in a direction parallel withthe plane in which microlenses 1 a are arranged) of grooves 20 in alattice form formed in the microlens array 1 increases gradually fromthe side of the microlens 1 a to the side of the surface facing thesolid-state imaging device 3. In this respect, Embodiment 2 is differentfrom Embodiment 1 in which the width of the grooves 20 is substantiallyconstant. By changing the width of the grooves 20 as in the presentembodiment, the microlens array 1 can be released easily from a moldwhen it is resin-molded, so that the productivity improves.

The microlens array 1 is similar to that shown in FIG. 3 in that thelateral surfaces of the grooves 20 are coated with a light-absorbingblack coating 25.

In the case where the width of the grooves 20 is changed as in thepresent embodiment, it is possible to omit the black coating on thelateral surfaces 24 of the grooves 20 as shown in FIG. 8. The reason isthat, when stray light emitted from the quadratic prism portion 22 tothe inside of the groove 20 enters the lateral surface 24 of theadjacent quadratic prism portion 22, its incident angle is large, sothat it is more likely to be reflected without entering this quadraticprism portion 22, thus reducing the influence of the stray lightsufficiently.

EMBODIMENT 3

FIG. 9 is a partially broken perspective view showing an imagingapparatus according to Embodiment 3 of the present invention. FIG. 10 isa sectional view showing a microlens array 1 used in the imagingapparatus according to Embodiment 3. The elements that are the same asthose in Embodiment 1 are assigned the same reference numerals, and thedescription thereof will be omitted.

In Embodiment 3, a black resin 30 is filled in slit grooves 20 formed ina lattice form along a border between adjacent image forming units 5 inthe surface of the microlens array 1 on the side of a solid-stateimaging device 3. The resin 30 is formed of a material having a smallerlight transmittance than a material of the microlens array 1 includingmicrolenses 1 a.

Since light that has passed through the microlens 1 a and then enteredthis groove 20 is absorbed by the black resin 30, it does not passthrough the black resin 30 and does not enter the adjacent quadraticprism portion 22.

Also, by filling the resin 30 into the grooves 20, the strength of themicrolens array 1 increases, thus achieving easier handling whenassembling the apparatus.

Further, in the case where the material of the resin 30 has a largerrefractive index than that of the microlens array 1, light entering aninterface between the quadratic prism portion 22 and the resin 30 fromthe quadratic prism portion 22 is not totally-reflected easily by thisinterface, so that the stray light is absorbed by the resin 30 moreeasily. Thus, the influence of the stray light can be reduced further.

Although FIG. 10 has described the case where the width of the grooves20 (or the black resin 30) is constant in the thickness direction, thewidth also may increase gradually from the side of the microlens 1 a tothe side of the surface facing the solid-state imaging device 3similarly to Embodiment 2 (see FIGS. 7 and 8). In that case, an effectsimilar to that described in Embodiment 2 can be produced.

Other than the above, a description similar to Embodiment 1 applies tothe present embodiment.

EMBODIMENT 4

FIGS. 11A to 11D are sectional views showing a process sequence of anexample of a method for manufacturing a microlens array 1 according tothe present invention. Referring to these figures, the method formanufacturing the microlens array 1 will be described.

First, as shown in FIG. 11A, a plano-convex microlens array 1 whose onesurface is provided with a plurality of microlenses 1 a and whose othersurface is a flat surface 1 b is formed by resin molding (for example,injection molding).

Next, as shown in FIG. 11B, grooves 20 are formed in a lattice form fromthe side of the flat surface 1 b by laser processing.

Subsequently, as shown in FIG. 11C, a solution 27 prepared by dissolvinga black coating material in a solvent is poured into the grooves 20.

By drying the solution 27, a black coating 25 is completed on thelateral surfaces of the grooves 20 as shown in FIG. 11D.

By increasing the content of the black coating material in the solution27 in FIG. 11C and/or repeating the processes shown in FIGS. 11C and 11Dplural times, it is possible to obtain the microlens array 1 whosegrooves 20 are filled with the resin as illustrated in Embodiment 3.

Incidentally, the grooves 20 also can be processed by resin molding atthe same time with molding the microlenses 1 a instead of the laserprocessing.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The embodimentsdisclosed in this application are to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, all changes that come within the meaning and range ofequivalency of the claims are intended to be embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to any fields with no particularlimitation but can be used preferably in a thin imaging apparatus suchas a card-shaped camera apparatus.

1. An imaging apparatus, comprising: an imaging device comprising aplurality of pixels having a photoelectric conversion function; and amicrolens array comprising a plurality of microlenses that form subjectimages on the plurality of pixels in the imaging device and are arrangedin a matrix; wherein the microlens array comprises grooves in a latticeform between the microlenses that are adjacent to each other, and adepth of the grooves is larger than a half of a thickness of themicrolens array.
 2. The imaging apparatus according to claim 1, whereina material of the microlens array comprises a light-transmitting resin.3. The imaging apparatus according to claim 1, wherein the microlensarray is a plano-convex lens array whose one surface is provided withthe microlenses and whose other surface is provided with the grooves andfaces the imaging device.
 4. The imaging apparatus according to claim 1,wherein a light-absorbing material is applied to lateral surfaces of thegrooves.
 5. The imaging apparatus according to claim 4, wherein thelight-absorbing material is black.
 6. The imaging apparatus according toclaim 1, wherein a width of the grooves increases toward the imagingdevice.
 7. The imaging apparatus according to claim 1, wherein a secondmaterial having a smaller light transmittance than a first materialforming the microlens array is filled in the grooves.
 8. The imagingapparatus according to claim 7, wherein the second material comprises amaterial having a light-absorption function.
 9. The imaging apparatusaccording to claim 7, wherein the second material has a largerrefractive index than the first material.
 10. The imaging apparatusaccording to claim 1, wherein the microlens array is manufactured by aresin molding.
 11. A method for manufacturing a microlens array,comprising: obtaining by a resin molding a microlens array whose onesurface is provided with a plurality of spherical or asphericalmicrolenses and whose other surface is flat; and forming grooves in alattice form on the other surface of the microlens array by a lightirradiation from the other surface.
 12. The method for manufacturing amicrolens array according to claim 11, further comprising processinglateral surfaces of the grooves to be black by injecting a solutionprepared by dissolving a black coating material in a solvent into thegrooves.
 13. A method for manufacturing a microlens array, comprising:obtaining a microlens array whose one surface is provided with aplurality of spherical or aspherical microlenses and whose other surfaceis provided with grooves in a lattice form and is flat except for thegrooves; and processing lateral surfaces of the grooves to be black byinjecting a solution prepared by dissolving a black coating material ina solvent into the grooves.